Transmission for vehicle and method for operation of a transmission

Abstract

A method of operating dual-clutch transmission for a vehicle which has two partial transmissions, each partial transmission having an input shaft arranged on an input shaft axis. An output shaft is arranged on the input shaft axis or a parallel countershaft axis. An intermediate gear system on the countershaft axis. At least one input shaft can be connected to the drive output shaft, as a direct drive, and only one countershaft is arranged on the countershaft axis and supports only fixed gears. One of the gears is a direct gear so that, when the direct gear is engaged, all the shifting elements, for coupling the intermediate gear system via the gear planes into the force flow, can be disengaged. Each gear plane can be coupled by a shifting element arranged on the input shaft axis to a shaft, and the gear next-lower than the direct gear is a coupling gear.

The invention claimed is: 
     
       1. A method of operating a dual-clutch transmission for a motor vehicle which comprises at least first and second partial transmissions ( 2 ,  3 ), each of the first and the second partial transmissions ( 2 ,  3 ) having at least one input shaft (EW 1 , EW 2 ) on a drive input side (AN) of the transmission ( 1 ), which are arranged on an input shaft axis ( 4 ), and an output shaft as a drive output shaft (AW) of the first and the second partial transmissions ( 2 ,  3 ) on a drive output side (AB) of the transmission ( 1 ), the method comprising the steps of:
 arranging the drive output shaft (AW) on the input shaft axis ( 4 ), an intermediate gear system ( 6 ) having two countershafts, each of the countershafts being arranged on a respective countershaft axis ( 5   a ,  5   b ), 
 connecting at least one of the input shafts (EW 1 , EW 2 ) to the drive output shaft (AW) by at least one of: 
 at least one gear plane (I, II, III, IV, R), and 
 at least one shifting element (A to H, J, L), 
 arranging at least four forward gear planes (I, II, III, IV, V) for obtaining a plurality of forward gears and arranging a reverse gear plane for obtaining at least one reverse gear, and each of the forward gear planes and the reverse gear plane comprises fixed gears, 
 providing at least six shifting elements (A to H, J, L), 
 arranging only one of the two countershafts (VW 1   a ; VW 1   b ) on each of the countershaft axes, ( 5   a ,  5   b ), each of the countershafts only having the fixed gears of the forward gear planes and the reverse gear plane as transmission elements, and fixing the fixed gears of the reverse gear plane on an output side end of the countershafts such that the reverse gear plane is an axially final gear plane along the countershaft axes, 
 obtaining at least the plurality of forward gears (V 1  to V 14 ) and the at least one reverse gear (R 1  to R 4 ) via the transmission ( 1 ), 
 forming at least one of the plurality of forward gears obtainable by the transmission ( 1 ) as a direct gear (V 5 , V 11 ; V 5 , V 10 ) such that, when the direct gear (V 5 , V 11 ; V 5 , V 10 ) is engaged, all the shifting elements for coupling the intermediate gear system ( 6 ), via the forward and the reverse gear planes, into a force flow are disengaged, and 
 each of the forward and the reverse gear planes (I to V, R) is couplable, by a respective one of the at least six shifting elements (A to H) arranged on the input shaft axis ( 4 ), to one of the input shafts, the output shaft and the countershafts (EW 1 , EW 2 , SW, HRW, PTW), and one of the plurality of forward gears (V 5 , V 12 ; V 5 , V 11 ) that is next-lower than the direct gear (V 6 , V 13 ; V 6 , V 12 ) is a coupling gear. 
 
     
     
       2. The method according to  claim 1 , further comprising the step of associating the next-lower gear (V 5 , V 12 ; V 5 , V 11 ), designed as the coupling gear, and associating another gear (V 4 , V 11 ; V 4 , V 10 ) that is next-lower than the coupling gear (V 5 , V 12 ; V 5 , V 11 ) with the second partial transmission ( 3 ) and associating the direct gear (V 6 , V 13 ; V 6 , V 12 ) with the first partial transmission ( 2 ). 
     
     
       3. The method according to  claim 1 , further comprising the step of achieving the force flow from the drive input side (AN) to the drive output side (AB) for the coupling gear (V 5 , V 12 ; V 5 , V 11 ) from the input shaft axis ( 4 ), by way of the intermediate gear system ( 6 ) and back to the input shaft axis ( 4 ), and thereafter analogously to a force flow of the direct gear (V 6 , V 13 ; V 6 , V 12 ). 
     
     
       4. The method according to  claim 1 , further comprising the step of engaging gears (V 4 , V 5 ; V 10 , V 11 ) that are directly adjacent in one of the first and the second partial transmissions ( 3 ) by a supported gearshift. 
     
     
       5. The method according to  claim 4 , further comprising the step of preselecting the direct gear (V 6 , V 13 ; V 6 , V 12 ), when two next-lower gears (V 4 , V 5 ; V 10 , V 11 ) are engaged before the direct gear (V 6 , V 13 ; V 6 , V 12 ). 
     
     
       6. The method according to  claim 4 , further comprising the step of supporting traction force for the supported gearshift by way of the direct gear (V 6 , V 13 ; V 6 , V 12 ) and via the first partial transmission ( 2 ), with which two next-lower gears (V 4 , V 5 ; V 10 , V 11 ) before the direct gear (V 6 , V 13 ; V 6 , V 12 ) are not associated. 
     
     
       7. The method according to  claim 1 , further comprising the steps of arranging a planetary gearset (GP) on the drive output shaft (AW) of the transmission ( 1 ), and the drive output shaft (AW) is a sun gear shaft (SW) of the planetary gearset (GP) and forming a new drive output shaft (AW) of the transmission ( 1 ) via a planetary carrier shaft (PTW),
 arranging the at least four forward gear planes, from the drive input side to the drive output side of the transmission, in an order of a first forward gear plane, a second forward gear plane, a third forward gear plane and a fourth forward gear plane such that the sun gear shaft is connectable, between the third and the fourth forward gear planes, only to one of the input shafts. 
 
     
     
       8. The method according to  claim 7 , further comprising the steps of coupling the sun gear shaft (SW) to a ring gear shaft (HRW) of the planetary gearset (GP) in order to provide a transmission ratio of 1, and arranging the second and the third forward gear planes such that, between the second and the third forward gear planes, only the third forward gear plane is connectable to the one of the input shafts. 
     
     
       9. The method according to  claim 1 , further comprising the step of, starting from the direct gear (V 6 , V 13 ; V 6 , V 12 ), achieving a direct powershift from a next-but-one lower gear (V 4 , V 10 ) to the direct gear (V 6 , V 13 ; V 6 , V 12 ). 
     
     
       10. The method according to  claim 1 , further comprising the step of achieving a force flow from the drive input side (AN) to the drive output side (AB) in at least one of the forward and the reverse gears by way of the intermediate gear system ( 6 ) having the respective countershafts (VW 1   a , VW 1   b ) on the two countershaft axes ( 5   a ,  5   b ). 
     
     
       11. The method according to  claim 6 , further comprising the step of obtaining at least 11 forward gears (V 1  to V 11 ) and at least four reverse gears (R 1  to R 4 ) by the transmission ( 1 ). 
     
     
       12. The method according to  claim 1 , further comprising the step of geometrically grading gears of the transmission ( 1 ). 
     
     
       13. The method according to  claim 1 , further comprising the step of operating the transmission with six gear planes (I to V, R) and seven shifting elements (A to H, J, L). 
     
     
       14. A dual-clutch transmission for a motor vehicle, the transmission comprising:
 at least two partial transmissions ( 2 ,  3 ), and each of the partial transmissions ( 2 ,  3 ) having at least one input shaft (EW 1 , EW 2 ) on a drive input side (AN) of the transmission ( 1 ) which are arranged on an input shaft axis ( 4 ); 
 an output shaft as a drive output shaft (AW) of the at least two partial transmissions ( 2 ,  3 ) on a drive output side (AB) of the transmission ( 1 ), and the drive output shaft (AW) being arranged on the input shaft axis ( 4 ); 
 an intermediate gear system ( 6 ) having two countershafts that are arranged on a respective countershaft axis ( 5   a ,  5   b ); 
 at least one of the input shafts (EW 1 , EW 2 ) is connectable to the drive output shaft (AW) by at least one gear plane (I, II, III, IV, R) and at least one shifting element (A, B, D to H, J, L); 
 at least six shifting elements (A to G); 
 on each of the countershaft axes ( 5   a ,  5   b ), only one of the countershafts (VW 1   a ; VW 1   b ) is arranged, and each of the countershafts only has fixed gears as transmission elements, 
 a plurality of forward gears (V 1  to V 11 ) and a plurality of reverse gears (R 1  to R 3 ) are engagable by the transmission ( 1 ), and at least one of the forward gears engagable by the transmission ( 1 ) is a direct gear (V 5 , V 10 ); 
 only first, second, third and fourth forward gear planes (I, II, III, IV) are provided for obtaining the plurality of forward gears and via the first, the second, the third and the fourth forward gear planes (I, II, III, IV) and via six shifting elements (A, B, D, E, F, G), at least 6 forward gears (V 1  to V 6 ) are engagable; a reverse gear plane is provided for obtaining a plurality of reverse gears, each of the first, the second, the third and the fourth forward gear planes and the reverse gear plane comprises two of the fixed gears of the countershafts and a loose gear rotatably supported about the input shaft axis, and the transmission ( 1 ) is designed such that at least all gearshifts between adjacent forward gears are powershiftable; 
 the first, the second, the third and the fourth forward gear planes and the reverse gear plane are arranged axially along the countershafts from the drive input side to the drive output side of the transmission in an order of the first forward gear plane, the second forward gear plane, the third forward gear plane, the fourth forward gear plane, and the reverse gear plane; 
 the fourth forward gear plane and the reverse gear plane are connectable to the drive output shaft at an axial location between the fourth forward gear plane and the reverse gear plane. 
 
     
     
       15. The transmission according to  claim 14 , wherein the reverse gear plane (R) is arranged downstream from the first, the second, the third and the fourth gear planes relative to a force flow from the drive input side to the drive output side (AB), and at least one of the six shifting elements is axially located between the fourth gear plane and the reverse gear stage. 
     
     
       16. The transmission according to  claim 14 , wherein at an axial location between the third and the fourth forward gear planes, the drive output shaft is directly connectable to only the input shafts (EW 1 , EW 2 ). 
     
     
       17. The transmission according to  claim 14 , wherein a planetary gearset (GP) is arranged on the drive output shaft (AW) of the transmission ( 1 ), in such manner that the drive output shaft (AW) is a sun gear shaft (SW) of the planetary gearset (GP) and a planetary carrier shaft (PTW) is the drive output shaft (AW) of the transmission ( 1 ), and a ring gear shaft of the planetary gearset is directly connectable to the sun gear shaft. 
     
     
       18. The transmission according to  claim 14 , wherein an electric machine (EM) is arranged on at least one of:
 at least one transmission element of a gear plane (I, II, III, IV, R), 
 at least one countershaft (VW 1   a , VW 1   b ), and 
 at least one of the shafts (EW 1 , EW 2 , SW) on the input shaft axis ( 4 ) 
 in order to hybridize the transmission ( 1 ) via at least one of an additional shifting element and a transmission element connected thereto. 
 
     
     
       19. The transmission according to  claim 14 , wherein all of the shifting devices (SE 1 , SE 3 , SE 4 , SE 6 ), except one shifting device (SE 2 ), are shifting devices which have two shifting elements. 
     
     
       20. The transmission according to  claim 14 , wherein the transmission ( 1 ) is designed in a geometrically graded manner. 
     
     
       21. The transmission according to  claim 17 , wherein one of the gear planes (IV) is a drive output constant and is couplable to a carrier (PT) of the planetary gearset (GP). 
     
     
       22. The transmission according to  claim 21 , wherein the drive output constant (IV) is couplable to the carrier (PT) of the planetary gearset (GP) by a further shifting element (J) located between the drive output constant (IV) and the planetary gearset (GP). 
     
     
       23. The transmission according to  claim 17 , wherein to shift the planetary gearset (GP), two shifting elements (L, H) arranged in a shifting device are provided, which when a further shifting element (J) is arranged on the drive output side (AB), are arranged on the drive input side (AN) of the planetary gearset (GP). 
     
     
       24. The transmission according to  claim 14 , wherein the transmission is incorporated within one of a passenger vehicle or a truck.